Purpose: To assess the current techniques of ophthalmic anesthesia in Nigeria.Materials and Methods: A cross sectional survey among Nigerian ophthalmology delegates attending the 36 th Annual Scientific Congress of the Ophthalmology Society of Nigeria. Self administered and anonymous questionnaires were used and data were collected to include details of the institution, preferred local anesthesia techniques, the grade of doctor who administers the local anesthesia, complications, preferred facial block techniques (if given separately), and type of premedication (if used).Results: Out of the 120 questionnaires distributed, 81 forms were completed (response rate 67.5%). Out of the 74 who indicated their grade, 49 (66.2%) were consultants, 22 (29.7%) were trainees, and 3 (7.1%) were ophthalmic medical officers. For cataract surgery, peribulbar anesthesia was performed by 49.1% of the respondents, followed by retrobulbar anesthesia (39.7%). Others techniques used were topical anesthesia (5.2%), subtenon anesthesia (4.3%), subconjunctival anesthesia (2.6%), and intracameral anesthesia (0.9%). For glaucoma surgery, 47.2% of the respondents use peribulbar anesthesia, 32.1% use retrobulbar anesthesia, 9.4% used general anesthesia, and 6.6% used subconjunctival anesthesia. Among the trainees, 57.8% routinely perform retrobulbar anesthesia while 55.6% routinely perform peribulbar anesthesia. At least one complication from retrobulbar anesthesia within 12 months prior to the audit was reported by 25.9% of the respondents. Similarly, 16.1% of the respondents had experienced complications from peribulbar anesthesia within the same time period. Retrobulbar hemorrhage is the most common complication experienced with both peribulbar and retrobulbar anesthesia.Conclusion: Presently, the most common technique of local anesthesia for an ophthalmic procedure in Nigeria is peribulbar anesthesia, followed by retrobulbar anesthesia. Twelve months prior to the study, 25.9% of the respondents had experienced at least one complication from retrobulbar anesthesia and 16.1% from peribulbar anesthesia. Retrobulbar hemorrhage was the most common complication reported.

Anesthesia is a very crucial part of any surgical procedure and includes ophthalmic procedures also. Ophthalmic surgery is unique; the majority of adult ophthalmic procedures are performed under local anesthesia [1] and this is often administered by a member of the ophthalmic team. Over the past two decades, anesthetic techniques in ophthalmology have evolved worldwide [2],[3],[4] with emphasis on ease of administration, adequate anesthesia of ocular tissues and akinesia of extraocular and orbicularis oculi muscles. The success of the surgical procedure may be influenced by the quality of anesthesia.

Ophthalmic anesthesia practices and preferences vary in different countries and the choice of technique is influenced by several factors, such as the nature of surgery, surgical experience, and skill of the surgeon as well as the level of cooperation of the patient. However, there is paucity of data on current techniques of ophthalmic anesthesia in Nigeria. The result of this audit would therefore help to establish a baseline and hopefully help identify possible areas of improvement.

A total of 120 self administered and anonymous questionnaires were distributed to participants. There were verbal reminders throughout the 4-day period of the conference for delegates to return the completed questionnaire. Information in the questionnaire include the type of institution, types of anesthetic techniques used for ophthalmic surgery, the grade of the individual who administers the anesthetic, nature of complications observed in the 12 months prior to the audit, facial block (if administered), and type of premedication (if used).

To maintain confidentiality, participant demographics such as age, gender, and name of their institutions were not included in the questionnaire. A pilot survey of the questionnaire was performed 5 months earlier among trainee ophthalmologists attending a clinical revision course. Ethics approval was obtained from the ethical committee of Lagos State University Teaching Hospital (LASUTH). Data analysis was performed with the Statistical Package for Social Sciences version 17 (SPSS, Chicago, IL, USA). Frequency table and descriptive statistics were generated for the variables.

Results

A total of 120 questionnaires were distributed to eligible delegates and 81 complete forms were returned (response rate 67.5%). Out of the 74 who indicated their grade, 49 (66.2%) were consultant ophthalmologists, 22 (29.7%) were trainees, and 3 (7.1%) were ophthalmic medical officers. Of the 71 responders who indicated their type of institutions, 53 (74.7%) were from tertiary training institutions, 13 (18.3%) from secondary care centers, and 5 (7.0%) from private hospitals.

Techniques for local anesthesia in ophthalmic surgery

Overall, our study [Table 1] suggests that peribulbar technique is the most frequently used method of administering local anesthesia (42%) followed by the retrobulbar technique (31%). However, up to 25 participants use more than one technique for ophthalmic surgery. About half of all strabismus surgery is done under general anesthesia with a quarter done by retrobulbar anesthesia. The majority of retinal surgery is performed under general anesthesia and just over a third is performed with peribulbar anesthesia [Figure 1].

Of the 77 participants who use facial block, 25 (32.5%) use a combination of Van Lints and O'Brien method, 14 (18.2%) use Van Lints only, 18 (23.4%) use O'Brien only, and 2 (2.6%) use Nadbath technique only. Eighteen (23.4%) participants do not routinely give a separate facial block.

Anesthetic complications

Twenty-one (25.9%) participants had experienced at least one complication from retrobulbar anesthesia in the preceding 12 months, 7 had experienced at least two complications, and 1 had experienced three complications within the same period. Retrobulbar hemorrhage was the most common complication. Other complications include insufficient block (6.7%) and globe perforation (3.3%).

Anesthetic complications from peribulbar technique were reported by 13 (16.1%) respondents and 4 respondents had two occurrences, making a total of 17 episodes. These reported complications include nine cases of retrobulbar hemorrhage, four subconjunctival hemorrhage, two chemosis, one insufficient block, and one inadvertent intravascular injection. There were no reported complications from subtenon anesthesia.

Discussion

Local anesthesia for routine ophthalmic procedures has evolved over the years, but the preferred option varies based on the country. The response rate in the current study was 67.5%, which we believe is reasonably high enough for generalization. The response rate is similar to the studies by Wagle et al.[5] (61.1%) in Singapore and Bellan et al.[6] (67%) in Canada.

Cataract and glaucoma surgery are probably the two most commonly performed operations by ophthalmologists all over the world. The choice of anesthesia technique can be influenced by factors such as a surgeon's preference, duration and type of surgery, and level of cooperation of the patient. This study revealed that nearly half of the respondents performed peribulbar anesthesia for cataract (49.1%) and glaucoma (47.2%) surgery. In recent surveys on ophthalmic anesthesia, topical anesthesia was the most common option for cataract surgery among ophthalmologists in the USA [7] and Canada. [8] Subtenon anesthesia was the most common option among ophthalmologists in the United Kingdom (UK), [9],[10] Japan, [11] and New Zealand. [12] However, peribulbar was the most common form of ophthalmic anesthesia among Singaporean ophthalmologists, [5] and this is similar to the findings of our study.

Retrobulbar anesthesia was the second most common technique, accounting for 37.9% of cataract and 32.1% of glaucoma surgery. In this respect, our findings differ from reports from other countries. In Singapore, for example, the preferred second choice of local anesthesia technique for cataract surgery was topical anesthesia with or without intracameral lignocaine. [9],[10],[11],[12] Similarly, retrobulbar injection was the least common method of local anesthesia in the UK. [9] Generally, the trend in ophthalmic anesthesia in various countries has shown a gradual shift from periocular anesthesia with sharp tipped instruments (needles) to blunt tipped instruments (cannula), [11] and ultimately to topical anesthesia (with or without intracameral anesthesia). For example, retrobulbar injection was the most common route of ocular anesthesia in Canada nearly 20 years ago, [6] but topical anesthesia is currently the preferred option. [8] The main reason against the use of periocular injection with sharp tipped instrument is to reduce the risk of injury to ocular and extraocular structures. This explains the increasing popularity of subtenon anesthetic technique as a safer alternative to retrobulbar and peribulbar anesthesia. [13],[14] Subtenon anesthesia is as effective as retrobulbar or peribulbar blocks in achieving ocular akinesia and anesthesia. [4],[13]

The use of a subtenon's route as a preferred method of local anesthesia was very low in our study, accounting for only 4.3% and 1.9% of cataract and glaucoma surgery, respectively. However, there is ongoing nationwide training on subtenon anesthesia in an attempt to increase the uptake of the technique.

A unique feature of ocular surgeries is the fact that the majority are performed under local anesthesia [1],[5],[11],[12],[15] and are frequently administered by a member of the ophthalmic team. Despite this, trained anesthetists play significant roles in regional/local ocular anesthesia in some countries. They are involved in administration of regional blocks and sedation, monitoring during surgery and management of emergency situations. In a national postal survey conducted in UK in 2008, 47% of subtenon and 85% of peribulbar blocks were performed by anesthetists. [10] In addition, in the 2002 survey of delegates to the Congress of International Council of Ophthalmology, there was intraoperative monitoring by a trained anesthetist in a high proportion of cases in Australia (97%), USA (96%), and Canada (83%). [15] Anesthetists played very little role in regional ocular anesthesia in this study, as only three (4.7%) and two (2.5%) respondents indicated that anesthetists gave retrobulbar and peribulbar blocks, respectively [Table 2].

Complications can occur from any anesthetic procedure irrespective of route of administration. In our study, a fair proportion of respondents experienced complications from retrobulbar (25.9%) and peribulbar (16.1%) anesthesia. Retrobulbar and peribulbar injections have been associated with a greater occurrence of sight threatening complications, [9],[16],[17],[18] compared with subtenon or topical routes. The most common serious complication reported in this study was retrobulbar hemorrhage.

To the best of our knowledge, this is the first report describing current practice of ophthalmic local anesthesia techniques in Nigeria. The current study shows that peribulbar and retrobulbar blocks are the two most common techniques. As we only surveyed ophthalmologists attending the 36 th Annual Ophthalmology Congress, this potentially could have created a selection bias. This limitation will be considered when the audit cycle is repeated. However, we believe the report was a fair representation of the current practice of ophthalmic local anesthesia techniques in Nigeria.